Initial version of the asynchronous API for PHP. Includes only the API itself and the necessary core changes required for the API to function.

…ized into a method for retrieving any ClassEntry.

  Now, using this API function, you can obtain the required class entry by a type descriptor type.

Added API functions for coroutine context management:
- zend_async_context_set_t: set value by string or object key
- zend_async_context_get_t: get value by string or object key
- zend_async_context_has_t: check if key exists
- zend_async_context_delete_t: delete key-value pair

Includes convenience macros for easier usage:
ZEND_ASYNC_CONTEXT_SET_STR/OBJ, GET_STR/OBJ, HAS_STR/OBJ, DELETE_STR/OBJ

Added complete Context API implementation:
- Updated zend_async_scheduler_register signature to accept context functions
- Added context function pointers and registration in zend_async_API.c
- Context API supports both string and object keys
- Includes convenience macros for easy usage

This completes the core API infrastructure for coroutine context management.

- Remove separate context_set, context_get, context_has, context_delete functions
- Add single zend_async_new_context_fn function to create context instances
- Move context implementation to ext/async module using zend_async_context_t structure
- Update scheduler registration to include new_context_fn parameter
- Add context field to zend_async_globals_t and zend_coroutine_s
- Simplify Context API macros to ZEND_ASYNC_NEW_CONTEXT and ZEND_ASYNC_CURRENT_CONTEXT

% removal of the current Scope from the global structure

… always needs to be explicitly known. Macros like ZEND_ASYNC_CURRENT_SCOPE were updated.

  A new macro ZEND_ASYNC_MAIN_SCOPE was added for the main Scope.

…main coroutine can correctly return control.

* add macro START_REACTOR_OR_RETURN for reactor autostart

… is now passed to the main coroutine’s finalize method instead of being displayed on screen.

* Fixed an issue with correctly passing the exception into the coroutine.

… captures the exception, marking it as handled in another coroutine.

…ync context